Genetic and histologic studies of somatomammotropic pituitary tumors in patients with the "complex of spotty skin pigmentation, myxomas, endocrine overactivity and schwannomas" (Carney complex)

Carney complex- why thorough medical history taking is so important - report of three cases and review of the literature

PURPOSE

To present a new case series and to review the literature on Carney complex (CNC) with an emphasis on highlighting key clinical features of the disease and pointing out possibilities of shortening the diagnostic process.

METHOD

Searches of PubMed, identifying relevant reports up to April 2022.

RESULTS

CNC is a rare, autosomally dominant inherited neoplasia -endocrinopathy syndrome with high clinical variability, even among members of the same family. Data on length of diagnostic process are scarce with numerous case series reporting a diagnostic delay of decades. Suggestions to shorten the diagnostic process includes awareness of the multi-faceted clinical presentations of CNC, thorough history taking of index patients and family members and awareness of diagnostic pitfalls. Importantly, unusual symptom combinations should alert the clinician to suspect a rare endocrinopathy syndrome such as CNC. Already present and coming on the horizon are databases and novel phenotyping technologies that will aid endocrinologists in their quest for timely diagnosis.

CONCLUSION

In this review, we examine the current state of knowledge in CNC and suggest avenues for shortening the diagnostic journey for the afflicted patients.

Genetic and clinical phenotypic analysis of carney complex with external auditory canal myxoma

Background: Mutations in PRKAR1A gene can lead to Carney complex (CNC), and most CNC patients develop cardiac and cutaneous myxomas. In particular, cardiac myxomas are a common cause of mortality in CNC patients. Cutaneous myxomas of the external ear are extremely rare, and do not have any specific clinical features

Methods: In this retrospective study, we analyzed the clinical and genetic data of the proband and his family and fifty whole blood control samples selected from the molecular genetic database of our hospital. Whole exome DNA sequencing analysis was used to detect the mutation in the peripheral blood samples.

Results: The results of the clinical analysis showed the presence of spotty skin pigmentation and external auditory canal myxoma in the proband as well as in his sister and mother. Whole-exome DNA sequencing showed a novel heterozygous mutation in the PRKAR1A gene i.e., c.824_825delAG (p.Gln275Leufs*2), in the proband and his sister and mother.

Conclusion: In conclusion, the family members had the same autosomal dominant PRKAR1A mutation. DNA sequencing revealed a novel c.824_825delAG in exon 9 of PRKAR1A. This pathogenic mutation has not been reported previously, and may be related to the occurrence of external auditory canal myxomas and spotty pigmentation. This study broadens the genotypic spectrum of PRKAR1A mutations in CNC.

Neurofibromatosis Type 1 Has a Wide Spectrum of Growth Hormone Excess

Overgrowth due to growth hormone (GH) excess affects approximately 10% of patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG). Our aim is to describe the clinical, biochemical, pathological, and genetic features of GH excess in a retrospective case series of 10 children and adults with NF1 referred to a tertiary care clinical research center. Six children (median age = 4 years, range of 3−5 years), one 14-year-old adolescent, and three adults (median age = 42 years, range of 29−52 years) were diagnosed with NF1 and GH excess. GH excess was confirmed by the failure to suppress GH (<1 ng/mL) on oral glucose tolerance test (OGTT, n = 9) and frequent overnight sampling of GH levels (n = 6). Genetic testing was ascertained through targeted or whole-exome sequencing (n = 9). Five patients (all children) had an OPG without any pituitary abnormality, three patients (one adolescent and two adults) had a pituitary lesion (two tumors, one suggestive hyperplasia) without an OPG, and two patients (one child and one adult) had a pituitary lesion (a pituitary tumor and suggestive hyperplasia, respectively) with a concomitant OPG. The serial overnight sampling of GH levels in six patients revealed abnormal overnight GH profiling. Two adult patients had a voluminous pituitary gland on pituitary imaging. One pituitary tumor from an adolescent patient who harbored a germline heterozygous p.Gln514Pro NF1 variant stained positive for GH and prolactin. One child who harbored a heterozygous truncating variant in exon 46 of NF1 had an OPG that, when compared to normal optic nerves, stained strongly for GPR101, an orphan G protein-coupled receptor causing GH excess in X-linked acrogigantism. We describe a series of patients with GH excess and NF1. Our findings show the variability in patterns of serial overnight GH secretion, somatotroph tumor or hyperplasia in some cases of NF1 and GH excess. Further studies are required to ascertain the link between NF1, GH excess and GPR101, which may aid in the characterization of the molecular underpinning of GH excess in NF1.

Prkar1a haploinsufficiency ameliorates the growth hormone excess phenotype in Aip-deficient mice

Mutations of the regulatory subunit (PRKAR1A) of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA), leading to activation of the PKA pathway, are the genetic cause of Carney complex which is frequently accompanied by somatotroph tumors. Aryl hydrocarbon receptor-interacting protein (AIP) mutations lead to somatotroph tumorigenesis in mice and humans. The mechanisms of AIP-dependent pituitary tumorigenesis are still under investigation and evidence points to a connection between the AIP and PKA pathways. In this study, we explore the combined effects of Aip and Prkar1a deficiency on mouse phenotype and, specifically, pituitary histopathology. Aip+/- mice were compared with double heterozygous Aip+/-, Prkar1a+/- mice. The phenotype (including histopathology and serological studies) was recorded at 3, 6, 9 and 12 months of age. Detailed pituitary histological and immunohistochemical studies were performed at 12 months. Twelve-month old Aip+/- mice demonstrated phenotypic and biochemical evidence of GH excess including significantly elevated insulin-like growth factor 1 levels, larger weight and body length, higher hemoglobin and cholesterol levels and a higher frequency of growth plate thickening in comparison to Aip+/, Prkar1a+/- mice. Pituitary histopathology did not uncover any pituitary adenomas or somatotroph hyperplasia in either group. These results demonstrate a slow progression from elevated GH release to the formation of overt somatotropinomas in Aip+/- mice; the acromegalic phenotype of these mice is surprisingly ameliorated in Aip+/-, Prkar1a+/- mice. This highlights the complexities of interaction between the AIP and PKA pathway. Specifically targeting GH secretion rather than somatotroph proliferation may be an advantage in the medical treatment of AIP-dependent human acromegaly.

Potential markers of disease behavior in acromegaly and gigantism

Introduction: Acromegaly and gigantism entail increased morbidity and mortality if left untreated, due to the systemic effects of chronic GH and IGF-1 excess. Guidelines for the diagnosis and treatment of patients with GH excess are well established; however, the presentation, clinical behavior and response to treatment greatly vary among patients. Numerous markers of disease behavior are routinely used in medical practice, but additional biomarkers have been recently identified as a result of basic and clinical research studies.Areas covered: This review focuses on genetic, molecular and genomic features of patients with GH excess that have recently been linked to disease progression and response to treatment. A PubMed search was conducted to identify markers of disease behavior in acromegaly and gigantism. Markers already considered as part of routine studies in clinical care guidelines were excluded. Literature search was expanded for each marker identified. Novel markers not included or only partially covered in previously published reviews on the subject were prioritized.Expert opinion: Recognizing the most relevant markers of disease behavior may help the medical team tailoring the strategies for approaching each case of acromegaly and gigantism. This customized plan should make the evaluation, treatment and follow up process more efficient, greatly improving the patients' outcomes.

The Genetics of Pituitary Adenomas

The genetic landscape of pituitary adenomas (PAs) is diverse and many of the identified cases remain of unclear pathogenetic mechanism. Germline genetic defects account for a small percentage of all patients and may present in the context of relevant family history. Defects in AIP (mutated in Familial Isolated Pituitary Adenoma syndrome or FIPA), MEN1 (coding for menin, mutated in Multiple Endocrine Neoplasia type 1 or MEN 1), PRKAR1A (mutated in Carney complex), GPR101 (involved in X-Linked Acrogigantism or X-LAG), and SDHx (mutated in the so called "3 P association" of PAs with pheochromocytomas and paragangliomas or 3PAs) account for the most common familial syndromes associated with PAs. Tumor genetic defects in USP8, GNAS, USP48 and BRAF are some of the commonly encountered tissue-specific changes and may explain a larger percentage of the developed tumors. Somatic (at the tumor level) genomic changes, copy number variations (CNVs), epigenetic modifications, and differential expression of miRNAs, add to the variable genetic background of PAs.

Acromegaly in Carney complex

PURPOSE

Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by mucocutaneous pigmentation, cardiac, cutaneous myxomas and endocrine overactivity. It is generally caused by inactivating mutations in the PRKAR1A (protein kinase cAMP-dependent type I regulatory subunit alpha) gene. Acromegaly is an infrequent manifestation of CNC, reportedly diagnosed in 10% of patients.

METHODS

We here report the case of a patient who was concomitantly diagnosed with Carney complex, due to a new mutation in PRKAR1A ((NM_002734.3:c.80_83del, p.(Ile27Lysfs*101 in exon 2), and acromegaly. In parallel, we conducted an extensive review of published case reports of acromegaly in the setting of CNC.

RESULTS

The 43-year-old patient was diagnosed with an acromegaly due to a GH-secreting pituitary microadenoma resistant to somatostatin analogs. He underwent transsphenoidal surgery in our tertiary referral center, which found a pure GH-secreting adenoma. In the literature, we identified 57 cases (24 men, 33 women) of acromegaly in CNC patients. The median age at diagnosis was 28.8 ± 12 year and there were 6 cases of gigantism. Acromegaly revealed CNC in only 4 patients. 24 patients had a microadenoma and two carried pituitary hyperplasia and/or multiple adenomas, suggesting that CNC may result in a higher proportion of microadenoma as compared to non-CNC acromegaly.

CONCLUSIONS

Although it rarely reveals CNC, acromegaly is diagnosed at a younger age in this setting, with a higher proportion of microadenomas.

Detection of new potentially pathogenic mutations in two patients with primary pigmented nodular adrenocortical disease (PPNAD) - case reports with literature review

INTRODUCTION

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare form of ACTH-independent Cushing's syndrome (CS). Half of patients with PPNAD are sporadic cases and the other half familial.

MATERIAL AND METHODS

We present two patients with PPNAD confirmed by genetic analysis.

RESULTS

In both patients there were no abnormal findings on diagnostic imaging of both adrenals and heart. Patients underwent bilateral two-stage adrenalectomy. Histopathological examination confirmed PPNAD. Genetic testing showed the following mutations in the PRKAR1A gene coding for the regulatory subunit type 1A of the protein kinase A enzyme: c.125dupG (patient 1) and c.15dupT (patient 2). Both these defects lead to inactivation of the PRKAR1A protein and are consequently causative of PPNAD in these patients.

CONCLUSIONS

The novel mutations presented in this article are considered to be pathogenic for PPNAD.

A novel splice site mutation of the PRKAR1A gene, C.440+5 G>C, in a Chinese family with Carney complex

BACKGROUND

Carney complex (CNC) is an extremely rare, multiple endocrine neoplasia syndrome that occurs in an autosomal dominant manner. Mutations in PRKAR1A have been reported to be a common genetic cause of CNC.

METHODS

In this study, we reported a Chinese pedigree of CNC that manifests mainly as spotty skin pigmentation and primary pigmented nodular adrenocortical disease. Whole blood samples of this pedigree were collected for DNA/RNA analysis. Polymerase chain reaction (PCR) and reverse-transcription polymerase chain reaction analyses were performed to amplify the 11 exons and adjacent introns of PRKAR1A. Direct sequencing was used to detect the mutation, and DNA from 70 Han Chinese people was extracted and sequenced as a control to estimate the frequency of the identified mutation.

RESULTS

Within the pedigree, ten patients with CNC were identified, and a novel heterozygous mutation (c.440+5 G>C in intron 4a) was identified in the PRKAR1A gene. PCR amplification of cDNA from the control subjects and patients was performed. Agarose gel electrophoresis showed only one wild-type band in the cDNA corresponding to the former group, whereas an extra band was present in samples from the latter group corresponding to the skipping of exon 4a; this confirms that the variant affects PRKAR1A splicing.

CONCLUSION

In conclusion, the c.440+5 G>C mutation is a new splice site mutation that has not been reported and has the potential to broaden the mutational spectrum of PRKAR1A that is associated with CNC, which would facilitate genetic diagnosis and counseling for CNC.

Surgical Management of Carney Complex-Associated Pituitary Pathology

BACKGROUND

Carney complex (CNC) is a familial neoplasia syndrome that is associated with pituitary-associated hypersecretion of growth hormone (GH) (acromegaly). The underlying cause of pituitary GH hypersecretion and its management have been incompletely defined.

OBJECTIVE

To provide biological insight into CNC-associated pituitary pathology and improve management, we analyzed findings in CNC patients who underwent transsphenoidal surgery.

METHODS

Consecutive CNC patients at the National Institutes of Health with acromegaly and imaging evidence of a pituitary adenoma(s) who underwent transsphenoidal resection of tumor(s) were included. Prospectively acquired magnetic resonance imaging and biochemical, surgical, and histological data were analyzed.

RESULTS

Seven acromegalic CNC patients (2 male, 5 female) were included. The mean age at surgery was 29.7 years (range, 18-44 years). The mean follow-up was 4.7 years (range, 0.2-129 months). Magnetic resonance imaging revealed a single pituitary adenoma in 4 patients and multiple pituitary adenomas in 3 patients. Whereas patients with single discrete pituitary adenomas underwent selective adenomectomy, patients with multiple adenomas underwent selective adenomectomy of multiple tumors, as well as partial or total hypophysectomy. All adenomas were either GH and prolactin positive or exclusively prolactin positive. Pituitary tissue surrounding the adenomas in patients with multiple adenomas revealed hyperplastic GH- and prolactin-positive tissue.

CONCLUSION

CNC-associated acromegaly results from variable pituitary pathology, including a single GH-secreting adenoma or multiple GH-secreting adenomas and/or GH hypersecretion of the pituitary gland surrounding multiple adenomas. Although selective adenomectomy is the preferred treatment for cases of GH-secreting adenomas, multiple adenomas with associated pituitary gland GH hypersecretion may require partial or complete hypophysectomy to achieve biochemical remission.

Growth hormone-producing pituitary adenomas in childhood and young adulthood: clinical features and outcomes

PURPOSE

Growth hormone (GH)-producing pituitary adenomas (PAs) in childhood or young adulthood are rare, and the details surrounding these tumors remain enigmatic. We present the clinical, pathological and genetic features of this disease.

METHODS

We identified 25 patients aged 20 years or younger with GH-producing PAs who underwent surgery between 2003 and 2016 at Toranomon Hospital in Tokyo. We retrospectively reviewed the clinical data, treatment outcomes and pathological features of these patients to shed light on childhood acromegaly.

RESULTS

The cohort comprised 14 male and 11 female patients whose average age at the time of surgery was 17.3 years. Germline AIP mutations were present in 5 of 13 patients examined, and Carney complex was identified in 2 of 25 patients. The mean maximum tumor diameter was 26.7 mm, and total resection assessed during surgery was achieved in 17 patients. Based on their respective pathological findings, patients were divided into the following 4 groups: sparsely granulated adenomas (5), densely granulated (DG) adenomas (6), plurihormonal adenomas (9), and silent subtype 3 (SS3) adenomas (5). During the mean follow-up period of 50.3 months, complete endocrinological remission was achieved in 14 of 25 patients (56%) by surgery alone and in 19 patients (76%) after postoperative adjuvant therapy.

CONCLUSIONS

GH-producing PAs in young patients are intriguing and difficult to treat due to their distinct tumor characteristics, including a lower incidence of the DG subtype and a higher incidence of SS3 adenomas and genetic abnormalities. Therefore, multi-modal therapies are essential to achieve optimal clinical outcomes.

Pediatric Pituitary Adenoma: Case Series, Review of the Literature, and a Skull Base Treatment Paradigm

Background  Pediatric pituitary adenoma is a rare skull base neoplasm, accounting for 3% of all intracranial neoplasms in children and 5% of pituitary adenomas. Compared with pituitary tumors in adults, secreting tumors predominate and longer disease trajectories are expected due to the patient age resulting in a natural history and treatment paradigm that is complex and controversial. Objectives  The aims of this study were to describe a large, single-institution series of pediatric pituitary adenomas with extensive long-term follow-up and to conduct a systematic review examining outcomes after pituitary adenoma surgery in the pediatric population. Methods  The study cohort was compiled by searching institutional pathology and operative reports using diagnosis and site codes for pituitary and sellar pathology, from 1956 to 2016. Systematic review of the English language literature since 1970 was conducted using PubMed, MEDLINE, Embase, and Google Scholar. Results  Thirty-nine surgically managed pediatric pituitary adenomas were identified, including 15 prolactinomas, 14 corticotrophs, 7 somatotrophs, and 4 non-secreting adenomas. All patients underwent transsphenoidal resection (TSR) as the initial surgical treatment. Surgical cure was achieved in 18 (46%); 21 experienced recurrent/persistent disease, with secondary treatments including repeat surgery in 10, radiation in 14, adjuvant pharmacotherapy in 11, and bilateral adrenalectomy in 3. At the last follow-up (median 87 months, range 3-581), nine remained with recurrent/persistent disease (23%). Thirty-seven publications reporting surgical series of pediatric pituitary adenomas were included, containing 1,284 patients. Adrenocorticotropic hormone (ACTH)-secreting tumors were most prevalent (43%), followed by prolactin (PRL)-secreting (37%), growth hormone (GH)-secreting (12%), and nonsecreting (7%). Surgical cure was reported in 65%. Complications included pituitary insufficiency (23%), permanent visual dysfunction (6%), chronic diabetes insipidus (DI) (3%), and postoperative cerebrospinal fluid (CSF) leak (4%). Mean follow-up was 63 months (range 0-240), with recurrent/persistent disease reported in 18% at the time of last follow-up. Conclusion  Pediatric pituitary adenomas are diverse and challenging tumors with complexities far beyond those encountered in the management of routine adult pituitary disease, including nuanced decision-making, a technically demanding operative environment, high propensity for recurrence, and the potentially serious consequences of hypopituitarism with respect to fertility and growth potential in a pediatric population. Optimal treatment requires a high degree of individualization, and patients are most likely to benefit from consolidated, multidisciplinary care in highly experienced centers.

Harvey Cushing Treated the First Known Patient With Carney Complex

Context:

Carney complex (CNC) is a syndrome characterized by hyperplasia of endocrine organs and may present with clinical features of Cushing syndrome and acromegaly due to functional adrenal and pituitary gland tumors. CNC has been linked to mutations in the regulatory subunit of protein kinase A type I-alpha (PRKAR1A) gene.

Design:

Tissue samples were taken from the hypothalamus or thalamus or tumors of patients with pituitary adenomas seen and operated on by neurosurgeon Harvey Cushing between 1913 and 1932. Following DNA extraction, sequencing for genes of interest was attempted, including PRKAR1A, AIP, USP8, GNAS1, and GPR101, to explore the possibility that these mutations associated with acromegaly, CNC, and Cushing syndrome have been conserved over time.

Results:

We report a patient described by Dr. Cushing in 1914 with a clinical presentation and postmortem findings suggestive of CNC. Genetic sequencing of the hypothalamus and pituitary adenoma revealed a germline heterozygous p.Arg74His mutation in the PRKAR1A gene, a codon previously described as mutated in CNC, but with a novel amino acid change.

Conclusions:

This patient is, to our knowledge, the first molecularly confirmed individual with CNC. This case demonstrates the power of modern genetics in studying archived tissues and the importance of recording detailed clinical notes in the diagnosis of disease.

Corticotropinoma as a Component of Carney Complex

Known germline gene abnormalities cause one-fifth of the pituitary adenomas in children and adolescents, but, in contrast with other pituitary tumor types, the genetic causes of corticotropinomas are largely unknown. In this study, we report a case of Cushing disease (CD) due to a loss-of-function mutation in PRKAR1A, providing evidence for association of this gene with a corticotropinoma. A 15-year-old male presenting with hypercortisolemia was diagnosed with CD. Remission was achieved after surgical resection of a corticotropin (ACTH)-producing pituitary microadenoma, but recurrence 3 years later prompted reoperation and radiotherapy. Five years after the original diagnosis, the patient developed ACTH-independent Cushing syndrome, and a diagnosis of primary pigmented nodular adrenocortical disease was confirmed. A PRKAR1A mutation (c.671delG, p.G225Afs*16) was detected in a germline DNA sample from the patient, which displayed loss of heterozygosity in the corticotropinoma. No other germline or somatic mutations of interest were found. As corticotropinomas are not a known component of Carney complex (CNC), we performed loss of heterozygosity and messenger RNA stability studies in the patient's tissues, and analyzed the effect of Prkar1a silencing on AtT-20/D16v-F2 mouse corticotropinoma cells. No PRKAR1A defects were found among 97 other pediatric CD patients studied. Our clinical case and experimental data support a role for PRKAR1A in the pathogenesis of a corticotroph cell tumor. This is a molecularly confirmed report of a corticotropinoma presenting in association with CNC. We conclude that germline PRKAR1A mutations are a novel, albeit apparently infrequent, cause of CD.

Growth hormone and risk for cardiac tumors in Carney complex

Carney complex (CNC) is a multiple neoplasia syndrome that is caused mostly by PRKAR1A mutations. Cardiac myxomas are the leading cause of mortality in CNC patients who, in addition, often develop growth hormone (GH) excess. We studied patients with CNC, who were observed for over a period of 20 years (1995-2015) for the development of both GH excess and cardiac myxomas. GH secretion was evaluated by standard testing; dedicated cardiovascular imaging was used to detect cardiac abnormalities. Four excised cardiac myxomas were tested for the expression of insulin-like growth factor-1 (IGF-1). A total of 99 CNC patients (97 with a PRKAR1A mutation) were included in the study with a mean age of 25.8 ± 16.6 years at presentation. Over an observed mean follow-up of 25.8 years, 60% of patients with GH excess (n = 46) developed a cardiac myxoma compared with only 36% of those without GH excess (n = 54) (P = 0.016). Overall, patients with GH excess were also more likely to have a tumor vs those with normal GH secretion (OR: 2.78, 95% CI: 1.23-6.29; P = 0.014). IGF-1 mRNA and protein were higher in CNC myxomas than in normal heart tissue. We conclude that the development of cardiac myxomas in CNC may be associated with increased GH secretion, in a manner analogous to the association between fibrous dysplasia and GH excess in McCune-Albright syndrome, a condition similar to CNC. We speculate that treatment of GH excess in patients with CNC may reduce the likelihood of cardiac myxoma formation and/or recurrence of this tumor.

MEN1, MEN4, and Carney Complex: Pathology and Molecular Genetics

Pituitary adenomas are a common feature of a subset of endocrine neoplasia syndromes, which have otherwise highly variable disease manifestations. We provide here a review of the clinical features and human molecular genetics of multiple endocrine neoplasia (MEN) type 1 and 4 (MEN1 and MEN4, respectively) and Carney complex (CNC). MEN1, MEN4, and CNC are hereditary autosomal dominant syndromes that can present with pituitary adenomas. MEN1 is caused by inactivating mutations in the MEN1 gene, whose product menin is involved in multiple intracellular pathways contributing to transcriptional control and cell proliferation. MEN1 clinical features include primary hyperparathyroidism, pancreatic neuroendocrine tumours and prolactinomas as well as other pituitary adenomas. A subset of patients with pituitary adenomas and other MEN1 features have mutations in the CDKN1B gene; their disease has been called MEN4. Inactivating mutations in the type 1α regulatory subunit of protein kinase A (PKA; the PRKAR1A gene), that lead to dysregulation and activation of the PKA pathway, are the main genetic cause of CNC, which is clinically characterised by primary pigmented nodular adrenocortical disease, spotty skin pigmentation (lentigines), cardiac and other myxomas and acromegaly due to somatotropinomas or somatotrope hyperplasia.

Hyperplasia in glands with hormone excess

Five syndromes share predominantly hyperplastic glands with a primary excess of hormones: neonatal severe primary hyperparathyroidism, from homozygous mutated CASR, begins severely in utero; congenital non-autoimmune thyrotoxicosis, from mutated TSHR, varies from severe with fetal onset to mild with adult onset; familial male-limited precocious puberty, from mutated LHR, expresses testosterone oversecretion in young boys; hereditary ovarian hyperstimulation syndrome, from mutated FSHR, expresses symptomatic systemic vascular permeabilities during pregnancy; and familial hyperaldosteronism type IIIA, from mutated KCNJ5, presents in young children with hypertension and hypokalemia. The grouping of these five syndromes highlights predominant hyperplasia as a stable tissue endpoint and as their tissue stage for all of the hormone excess. Comparisons were made among this and two other groups of syndromes, forming a continuum of gland staging: predominant oversecretions express little or no hyperplasia; predominant hyperplasias express little or no neoplasia; and predominant neoplasias express nodules, adenomas, or cancers. Hyperplasias may progress (5 of 5) to neoplastic stages while predominant oversecretions rarely do (1 of 6; frequencies differ P<0.02). Hyperplasias do not show tumor multiplicity (0 of 5) unlike neoplasias that do (13 of 19; P<0.02). Hyperplasias express mutation of a plasma membrane-bound sensor (5 of 5), while neoplasias rarely do (3 of 14; P<0.002). In conclusion, the multiple distinguishing themes within the hyperplasias establish a robust pathophysiology. It has the shared and novel feature of mutant sensors in the plasma membrane, suggesting that these are major contributors to hyperplasia.

Carney complex: an update

Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22-24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment and molecular etiology, including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing's syndrome.

Geographic-Related Differences of Pituitary Adenomas Hormone Profile: Analysis of Two Groups Coming from Southeastern and Eastern Europe

We compared the immunoprofile of pituitary adenomas from Romania and Moldova. One hundred and eighty cases coming from Romania (94 cases, group 1) and Moldova (86 cases, group 2) were assessed by immunohistochemistry regarding all six basic hormones expressed in pituitary adenomas. Specific differences and similarities were found and stated for both groups. In group 1, 70% of cases were pituitary adenomas positive for one hormone, 13% were plurihormonal, while 17% were negative. In group 2, 50,3% of the cases expressed only one hormone and 12,5% were negative for all hormones. The highest difference was observed for plurihormonal adenomas, found in about 37,2% of cases for group 2 (2.86 times higher for group 2 compared with group 1). A higher incidence of GH-secreting adenomas characterized group "1," while group "2" had the highest percent of LH-secreting adenomas, 55% of cases being positive. Triple association was noticed in 4.25% of cases of group 1 and in 8,13% out of total cases, from group 2. Four-hormone association was found only in group 2, noticed in 15,56% of the cases. The present paper highlights strong evidences of a particular and different immunoprofile of pituitary adenomas coming from Romania and Moldova.

Aggressive pituitary tumors

Pituitary adenomas are common intracranial tumors that are mainly considered as benign. Rarely, these tumors can exhibit an aggressive behavior, characterized by gross invasion of the surrounding tissues, resistance to conventional treatment leading to early and frequent recurrences. Even more rarely, pituitary tumors can give rise to cerebrospinal or systemic metastases qualifying as pituitary carcinomas according to the latest WHO definition. In the same classification, a subset of tumors with relatively distinct histopathological features was identified and defined as atypical adenomas designated to follow a more aggressive clinical course. This classification, although clinically useful, does not provide an accurate correlation between histopathological findings and the clinical behavior of these tumors, neither is it adequate to convey the precise features of 'aggressive' tumors. Thus, 'aggressive' pituitary adenomas need to be properly defined with clinical, radiological, histological and molecular markers in order to identify patients at increased risk of early recurrence or subsequent tumor progression. At present, no single marker or classification system of pituitary tumor aggressiveness exists, and clinically useful information in the literature is insufficient to guide diagnostic and therapeutic decisions. Treatment of patients with aggressive pituitary tumors is challenging since conventional treatments often fail, necessitating multiple surgical procedures with additional radiotherapy. Although traditional chemotherapy applied in other neuroendocrine tumors has not been shown to be efficacious, newer agents, particularly temozolomide, have shown promising results and are currently used despite the lack of data from a randomized prospective trial. Molecular targeted therapies such as mTOR and epidermal growth factor inhibitors have also been applied and might prove to be useful in the management of these patients. In the present review, we provide information regarding the epidemiology and clinical, histopathological and molecular features of aggressive pituitary tumors using recent employed definitions. In addition, we review currently employed therapeutic means providing a therapeutic algorithm and highlight the need to identify more specific disease-related and prognostic markers and the necessity for central registration of these tumors.

The role of genetic and epigenetic changes in pituitary tumorigenesis

Pituitary adenomas are one of the most common intracranial tumors. Despite their benign nature, dysregulation of hormone secretion causes systemic metabolic deterioration, resulting in high mortality and an impaired quality of life. Tumorigenic pathogenesis of pituitary adenomas is mainly investigated by performing genetic analyses of somatic mutations in the tumor or germline mutations in patients. Genetically modified mouse models, which develop pituitary adenomas, are also used. Genetic analysis in rare familial pituitary adenomas, including multiple endocrine neoplasia type 1 and type 4, Carney complex, familial isolated pituitary adenomas, and succinate dehydrogenases (SDHs)-mediated paraganglioma syndrome, revealed several causal germline mutations and sporadic somatic mutations in these genes. The analysis of genetically modified mouse models exhibiting pituitary adenomas has revealed the underlying mechanisms, where cell cycle regulatory molecules, tumor suppressors, and growth factor signaling are involved in pituitary tumorigenesis. Furthermore, accumulating evidence suggests that epigenetic changes, including deoxyribonucleic acid (DNA) methylation, histone modification, micro ribonucleic acids (RNAs), and long noncoding RNAs play a pivotal role. The elucidation of precise mechanisms of pituitary tumorigenesis can contribute to the development of novel targeted therapy for pituitary adenomas.

Does somatostatin have a role in the regulation of cortisol secretion in primary pigmented nodular adrenocortical disease (ppnad)? a clinical and in vitro investigation

CONTEXT

Somatostatin (SST) receptors (SSTRs) are expressed in a number of tissues, including the adrenal cortex, but their role in cortisol secretion has not been well characterized.

OBJECTIVES

The objective of the study was to investigate the expression of SSTRs in the adrenal cortex and cultured adrenocortical cells from primary pigmented nodular adrenocortical disease (PPNAD) tissues and to test the effect of a single injection of 100 μg of the SST analog octreotide on cortisol secretion in patients with PPNAD.

SETTING AND DESIGN

The study was conducted at an academic research laboratory and clinical research center. Expression of SSTRs was examined in 26 PPNAD tissues and the immortalized PPNAD cell line CAR47. Ten subjects with PPNAD underwent a randomized, single-blind, crossover study of their cortisol secretion every 30 minutes over 12 hours (6:00 pm to 6:00 am) before and after the midnight administration of octreotide 100 μg sc.

METHODS

SSTRs expression was investigated by quantitative PCR and immunohistochemistry. The CAR47 and primary cell lines were studied in vitro. The data of the 10 patients were analyzed before and after the administration of octreotide.

RESULTS

All SSTRs, especially SSTR1-3, were expressed in PPNAD at significantly higher levels than in normal adrenal. SST was found to differentially regulate expression of its own receptors in the CAR47 cell line. However, the administration of octreotide to patients with PPNAD did not significantly affect cortisol secretion.

CONCLUSIONS

SSTRs are overexpressed in PPNAD tissues in comparison with normal adrenal cortex. Octreotide did not exert any significant effect on cortisol secretion in a short clinical pilot study in a small number of patients with PPNAD, but long-acting SST analogs targeting multiple SSTRs may be worth investigating in this condition.

Pituitary adenoma with mucin cells in a man with an unusual presentation of Carney complex

We describe a 44-year-old man with infertility, acromegaly, and hypergonadotropic hypogonadism. Clinical examination of the patient revealed hyperpigmented macules on the lips, buccal mucosa, and face which were histologically confirmed as cutaneous myxomas and blue nevi. Ultrasound revealed testicular calcifications and multiple hypoechoic thyroid nodules. MR imaging showed a pituitary microadenoma and resection revealed it to be a growth hormone and prolactin-secreting adenoma with the unusual finding of admixed individual mucin-producing cells. We discuss mucin cells in pituitary adenoma, an unreported pathologic finding in a patient with Carney complex.

The complex of myxomas, spotty skin pigmentation and endocrine overactivity (Carney complex): imaging findings with clinical and pathological correlation

The complex of myxomas, spotty skin pigmentation and endocrine overactivity, or Carney complex (CNC), is a familial multiple endocrine neoplasia and lentiginosis syndrome. CNC is inherited in an autosomal dominant manner and is genetically heterogeneous. Its features overlap those of McCune-Albright syndrome and other multiple endocrine neoplasia (MEN) syndromes. Spotty skin pigmentation is the major clinical manifestation of the syndrome, followed by multicentric heart myxomas, which occur at a young age and are the lethal component of the disease. Myxomas may also occur on the skin (eyelid, external ear canal and nipple) and the breast. Breast myxomas, when present, are multiple and bilateral among female CNC patients, an entity which is also described as “breast-myxomatosis” and is a characteristic feature of the syndrome. Affected CNC patients often have tumours of two or more endocrine glands, including primary pigmented nodular adrenocortical disease (PPNAD), an adrenocorticotropin hormone (ACTH)-independent cause of Cushing’s syndrome, growth hormone (GH)-secreting and prolactin (PRL)-secreting pituitary adenomas, thyroid adenomas or carcinomas, testicular neoplasms (large-cell calcifying Sertoli cell tumours [LCCSCT]) and ovarian lesions (cysts and cancinomas). Additional infrequent but characteristic manifestations of CNC are psammomatous melanotic schwannomas (PMS), breast ductal adenomas (DAs) with tubular features, and osteochondromyxomas or “Carney bone tumour”.

Teaching Points

• Almost 60 % of the known CNC kindreds have a germline inactivating mutations in the PRKAR1A gene.

• Spotty skin pigmentation is the major clinical manifestation of CNC, followed by heart myxomas.

• Indicative imaging signs of PPNAD are contour abnormality and hypodense spots within the gland.

• Two breast tumours may present in CNC: myxoid fibroadenomas (breast myxomatosis) and ductal adenomas.

• Additional findings of CNC are psammomatous melanotic schwannomas (PMSs) and osteochondromyxomas.

Functional screen analysis reveals miR-26b and miR-128 as central regulators of pituitary somatomammotrophic tumor growth through activation of the PTEN-AKT pathway

MicroRNAs (miRNAs) have been involved in the pathogenesis of different types of cancer; however, their function in pituitary tumorigenesis remains poorly understood. Cyclic-AMP-dependent protein kinase-defective pituitaries occasionally form aggressive growth-hormone (GH)-producing pituitary tumors in the background of hyperplasia caused by haploinsufficiency of the protein kinase's main regulatory subunit, PRKAR1A. The molecular basis for this development remains unknown. We have identified a 17-miRNA signature of pituitary tumors formed in the background of hyperplasia (caused in half of the cases by PRKAR1A-mutations). We selected two miRNAs on the basis of their functional screen analysis: inhibition of miR-26b expression and upregulation of miR-128 suppressed the colony formation ability and invasiveness of pituitary tumor cells. Furthermore, we identified that miR-26b and miR-128 affected pituitary tumor cell behavior through regulation of their direct targets, PTEN and BMI1, respectively. In addition, we found that miR-128 through BMI1 direct binding on the PTEN promoter affected PTEN expression levels and AKT activity in the pituitary tumor cells. Our in vivo data revealed that inhibition of miR-26b and overexpression of miR-128 could suppress pituitary GH3 tumor growth in xenografts. Taken together, we have identified a miRNA signature for GH-producing pituitary tumors and found that miR-26b and miR-128 regulate the activity of the PTEN-AKT pathway in these tumors. This is the first suggestion of the possible involvement of miRNAs regulating the PTEN-AKT pathway in GH-producing pituitary tumor formation in the context of hyperplasia or due to germline PRKAR1A defects. MiR-26b suppression and miR-128 upregulation could have therapeutic potential in GH-producing pituitary tumor patients.

Familial gigantism

Familial GH-secreting tumors are seen in association with three separate hereditary clinical syndromes: multiple endocrine neoplasia type 1, Carney complex, and familial isolated pituitary adenomas.

Integrated genomic profiling identifies loss of chromosome 11p impacting transcriptomic activity in aggressive pituitary PRL tumors

Integrative genomics approaches associating DNA structure and transcriptomic analysis should allow the identification of cascades of events relating to tumor aggressiveness. While different genome alterations have been identified in pituitary tumors, none have ever been correlated with the aggressiveness. This study focused on one subtype of pituitary tumor, the prolactin (PRL) pituitary tumors, to identify molecular events associated with the aggressive and malignant phenotypes. We combined a comparative genomic hybridization and transcriptomic analysis of 13 PRL tumors classified as nonaggressive or aggressive. Allelic loss within the p arm region of chromosome 11 was detected in five of the aggressive tumors. Allelic loss in the 11q arm was observed in three of these five tumors, all three of which were considered as malignant based on the occurrence of metastases. Comparison of genomic and transcriptomic data showed that allelic loss impacted upon the expression of genes located in the imbalanced region. Data filtering allowed us to highlight five deregulated genes (DGKZ, CD44, TSG101, GTF2H1, HTATIP2), within the missing 11p region, potentially responsible for triggering the aggressive and malignant phenotypes of PRL tumors. Our combined genomic and transcriptomic analysis underlines the importance of chromosome allelic loss in determining the aggressiveness and malignancy of tumors.

Carney complex and other conditions associated with micronodular adrenal hyperplasias

Carney complex (CNC) is a multiple neoplasia syndrome that is inherited in an autosomal dominant manner and is characterized by skin tumors and pigmented lesions, myxomas, schwannomas, and various endocrine tumors. Inactivating mutations of the PRKAR1A gene coding for the regulatory type I-α (RIα) subunit of protein kinase A (PKA) are responsible for the disease in most CNC patients. The overall penetrance of CNC among PRKAR1A mutation carriers is near 98%. Most PRKAR1A mutations result in premature stop codon generation and lead to nonsense-mediated mRNA decay. CNC is genetically and clinically heterogeneous, with specific mutations providing some genotype-phenotype correlation. Phosphodiesterase-11A (the PDE11A gene) and -8B (the PDE8B gene) mutations were found in patients with isolated adrenal hyperplasia and Cushing syndrome, as well in patients with PPNAD. Recent evidences demonstrated that dysregulation of cAMP/PKA pathway can modulate other signaling pathways and contributes to adrenocortical tumorigenesis.

Solid tumors associated with multiple endocrine neoplasias

We present an update on molecular and clinical genetics of solid tumors associated with the various multiple endocrine neoplasias (MEN) syndromes. MEN type 1 (MEN1) describes the association of pituitary, parathyroid, and pancreatic islet cell tumors with a variety of many other lesions. MEN type 2 (MEN2) conditions represent at least four different syndromes that associate pheochromocytoma with medullary thyroid carcinoma, hyperparathyroidism, and a number of other manifestations. Other pheochromocytoma-associated syndromes include von Hippel-Lindau disease; neurofibromatosis 1; the recently defined paraganglioma syndromes type 1, 3, and 4; Carney-Stratakis syndrome; and the Carney triad. Carney-Stratakis syndrome is characterized by the association of paragangliomas and familial gastrointestinal stromal tumors. In the Carney triad, patients can manifest gastrointestinal stromal tumors, lung chondroma, paraganglioma, adrenal adenoma and pheochromocytoma, esophageal leiomyoma, and other conditions. The Carney complex is yet another form of MEN that is characterized by skin tumors and pigmented lesions, myxomas, schwannomas, and various endocrine neoplasias.

PRKAR1A and the evolution of pituitary tumors

Carney complex (CNC) is an inherited tumor predisposition associated with pituitary tumors, including GH-producing pituitary adenomas and rare reports of prolactinomas. This disease is caused by mutations in PRKAR1A, which encodes the type 1A regulatory subunit of the cAMP-dependent protein kinase, PKA. Loss of PRKAR1A causes enhanced PKA signaling, which leads to pituitary tumorigenesis. Mutations in the gene have not been detected in sporadic pituitary tumors, but there is some data to suggest that non-genomic mechanisms may cause loss of protein expression. Unlike CNC patients, mice heterozygous for Prkar1a mutations do not develop pituitary tumors, although complete knockout of the gene in the Pit1 lineage of the pituitary produces GH-secreting pituitary adenomas. These data indicate that complete loss of Prkar1a/PRKAR1A is able to cause pituitary tumors in mice and men. The pattern of tumors is likely related to the signaling pathways employed in specific pituitary cell types.

Anterior pituitary adenomas: inherited syndromes, novel genes and molecular pathways

Pituitary adenomas are common tumors. Although rarely malignant, pituitary adenomas cause significant morbidity due to mass effects and/or hormonal hypo- and/or hyper-secretion. Molecular understanding of pituitary adenoma formation is essential for the development of medical therapies and the treatment of post-operative recurrences. In general, mutations in genes involved in genetic syndromes associated with pituitary tumors are not a common finding in sporadic lesions. By contrast, multiple endocrine neoplasia type 1 (MEN-1) and aryl hydrocarbon receptor-interacting protein (AIP) mutations may be more frequent among specific subgroups of patients, such as children and young adults, with growth hormone-producing adenomas. In this article, we present the most recent data on the molecular pathogenesis of pituitary adenomas and discuss some of the most recent findings from our laboratory. Guidelines for genetic screening and clinical counseling of patients with pituitary tumors are provided.

Use of the metallothionein promoter-human growth hormone-releasing hormone (GHRH) mouse to identify regulatory pathways that suppress pituitary somatotrope hyperplasia and adenoma formation due to GHRH-receptor hyperactivation

Hyperactivation of the GHRH receptor or downstream signaling components is associated with hyperplasia of the pituitary somatotrope population, in which adenomas form relatively late in life, with less than 100% penetrance. Hyperplastic and adenomatous pituitaries of metallothionein promoter-human GHRH transgenic (Tg) mice (4 and > 10 months, respectively) were used to identify mechanisms that may prevent or delay adenoma formation in the presence of excess GHRH. In hyperplastic pituitaries, expression of the late G(1)/G(2) marker Ki67 increased, whereas the proportion of 5-bromo-2'-deoxyuridine-labeled cells (S phase marker) did not differ from age-matched controls. These results indicate cell cycle progression is blocked, with further evidence suggesting that enhanced p27 activity may contribute to this process. For adenomas, formation was associated with loss of p27 activity (nuclear localization and mRNA). Increased endogenous somatostatin (SST) tone may also slow the conversion from hyperplastic to adenomatous state because mRNA levels for SST receptors, sst2 and sst5, were elevated in hyperplastic pituitaries, whereas adenomas were associated with a decline in sst1 and sst5 mRNA. Also, SST-knockout Tg pituitaries were larger and adenomas formed earlier compared with those of SST-intact Tg mice. Unexpectedly, these changes were independent of changes in proliferation rate within the hyperplastic tissue, suggesting that endogenous SST controls GHRH-induced adenoma formation primarily via modulation of apoptotic and/or cellular senescence pathways, consistent with the predicted function of some of the most differentially expressed genes (Casp1, MAP2K1, TNFR2) identified by membrane arrays and confirmed by quantitative real-time RT-PCR.

Advances in the Diagnosis, Treatment, and Molecular Genetics of Pituitary Adenomas in Childhood

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Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics

Pituitary tumors are rare in childhood and adolescence, with a reported prevalence of up to one per 1 million children. Only 2-6% of surgically treated pituitary tumors occur in children. Although pituitary tumors in children are almost never malignant and hormonal secretion is rare, these tumors may result in significant morbidity. Tumors within the pituitary fossa are mainly of two types: craniopharyngiomas and adenomas. Craniopharyngiomas cause symptoms by compressing normal pituitary, causing hormonal deficiencies and producing mass effects on surrounding tissues and the brain; adenomas produce a variety of hormonal conditions such as hyperprolactinemia, Cushing disease and acromegaly or gigantism. Little is known about the genetic causes of sporadic lesions, which comprise the majority of pituitary tumors, but in children, more frequently than in adults, pituitary tumors may be a manifestation of genetic conditions such as multiple endocrine neoplasia type 1, Carney complex, familial isolated pituitary adenoma and McCune-Albright syndrome. The study of pituitary tumorigenesis in the context of these genetic syndromes has advanced our knowledge of the molecular basis of pituitary tumors and may lead to new therapeutic developments.

Clinical and molecular genetics of acromegaly: MEN1, Carney complex, McCune-Albright syndrome, familial acromegaly and genetic defects in sporadic tumors

Pituitary tumors are among the most common neoplasms in man; they account for approximately 15% of all primary intracranial lesions (Jagannathan et al., Neurosurg Focus, 19:E4, 2005). Although almost never malignant and rarely clinically expressed, pituitary tumors may cause significant morbidity in affected patients. First, given the critical location of the gland, large tumors may lead to mass effects, and, second, proliferation of hormone-secreting pituitary cells leads to endocrine syndromes. Acromegaly results from oversecretion of growth hormone (GH) by the proliferating somatotrophs. Despite the significant efforts made over the last decade, still little is known about the genetic causes of common pituitary tumors and even less is applied from this knowledge therapeutically. In this review, we present an update on the genetic syndromes associated with pituitary adenomas and discuss the related genetic defects. We next review findings on sporadic, non-genetic, pituitary tumors with an emphasis on pathways and animal models of pituitary disease. In conclusion, we attempt to present an overall, integrative approach to the human molecular genetics of both familiar and sporadic pituitary tumors.

Pituitary-specific knockout of the Carney complex gene Prkar1a leads to pituitary tumorigenesis

Carney complex (CNC) is an inherited neoplasia syndrome characterized by spotty skin pigmentation, myxomas, endocrine tumors, and schwannomas. Among the endocrine tumors that comprise the syndrome, GH-producing pituitary tumors are seen in approximately 10% of patients, although biochemical abnormalities of the GH axis are much more common. To explore the role of loss of the CNC gene PRKAR1A on pituitary tumorigenesis, we produced a tissue-specific knockout (KO) of this gene in the mouse. For these studies, we generated a mouse line expressing the cre recombinase in pituitary cells using the rat GHRH receptor promoter. These mice were then crossed with Prkar1a conditional null animals to produce tissue-specific KOs. Although prolactinomas were observed in KO and control mice, the KO mice exhibited a significantly increased frequency of pituitary tumors compared with wild-type or conventional Prkar1a(+/-) mice. Characterization of the tumors demonstrated they were composed of cells of the Pit1 lineage that stained for GH, prolactin, and TSH. At the biochemical level, levels of GH in the serum of KO animals were markedly elevated compared with controls, regardless of the presence of a frank tumor. These data indicate that complete loss of Prkar1a is sufficient to allow the formation of pituitary tumors and abnormalities of the GH axis, in close analogy to human patients with CNC.

Clonality of pituitary tumours: more complicated than initially envisaged?

The application of allelotype microsatellite polymorphisms and X chromosome inactivation analysis in samples from women allow assessment of clonality. Early studies showed that sporadic human pituitary tumors are benign adenomas of monoclonal origin. This implies that they arise from de novo somatic mutation(s) within a single pituitary cell. However, the evidence obtained from a number of studies indicate that morphology cannot predict clonality, clonality within a given tumour may be multiple or single, multiple tumours arising on the background of hyperplasia may be of identical or differing clonality, and multiple "sporadic" tumours within a gland may be of differing clonal origin. Thus, while the early available evidence indicated that pituitary tumours appear largely monoclonal, it is simplistic to assume that this is inevitable and that these cannot be multiclonal in origin. These observations would be entirely compatible with an initiating stimulus resulting in hyperplasia of specific cell types in the pituitary, which itself gives rise to several distinct clones with variable potential to develop into tumours. Such stimuli might include hypothalamic trophic factors, intrapituitary growth factors, or pituitary specific oncogenes.

PRKAR1A mutations in primary pigmented nodular adrenocortical disease

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare primary bilateral adrenal defect causing corticotropin-independent Cushing's syndrome. It occurs mainly in children and young adults. Macroscopic appearance of the adrenals is characteristic with small pigmented micronodules observed in the cortex. PPNAD is most often diagnosed in patients with Carney complex (CNC), but it can also be observed in patients without other manifestations or familial history (isolated PPNAD). The CNC is an autosomal dominant multiple neoplasia syndrome characterized by the association of myxoma, spotty skin pigmentation and endocrine overactivity. One of the putative CNC genes has been identified as the gene of the regulatory R1A subunit of protein kinase A (PRKAR1A), located at 17q22-24. Germline heterozygous inactivating mutations of PRKAR1A have been reported in about 45% of patients with CNC, and up to 80% of CNC patients with Cushing's syndrome due to PPNAD. Interestingly, such inactivating germline PRKAR1A mutations have also been found in patients with isolated PPNAD. The hot spot PRKAR1A mutation termed c.709[-7-2]del6 predisposes mostly to isolated PPNAD, and is the first clear genotype/phenotype correlation described for this gene. Somatic inactivating mutations of PRKAR1A have been observed in macronodules of PPNAD and in sporadic cortisol secreting adrenal adenomas. Isolated PPNAD is a genetic heterogenous disease, and recently inactivating mutations of the gene of the phosphodiesterase 11A4 (PDE11A4) located at 2q31-2q35 have been identified in patients without PRKAR1A mutations. Interestingly, both PRKAR1A and PDE11A gene products control the cAMP signaling pathway, which can be altered at various levels in endocrine tumors.

Pituitary pathology in patients with Carney Complex: growth-hormone producing hyperplasia or tumors and their association with other abnormalities

First described in the mid 80's, Carney Complex (CNC) is a rare, dominantly heritable disorder with features overlapping those of McCune-Albright syndrome (MAS) and other multiple endocrine neoplasia (MEN) syndromes like MEN type 1 (MEN 1). Pituitary tumors have been described in a number of patients with CNC; they present with elevated growth hormone (GH) levels and mild hyperprolactinemia. However, most patients with CNC have mild hypersomatomammotropinemia starting in adolescence; this is similar to the situation in MAS patients: in both disorders, pituitary hyperplasia appears to precede tumor development. Familial pituitary tumor syndromes such as CNC provide an important insight into the genetics and molecular pathology of pituitary and other endocrine tumors. Our understanding of these conditions is expanding rapidly due to the identification of the causative genes and the availability of murine disease models. The present report reviews the clinical findings related to pituitary tumor development among patients with CNC and provides an update on murine models of the complex.

Pituitary pathology in Carney complex patients

Carney complex (CNC) is a familial multiple neoplasia syndrome with features overlapping those of McCune-Albright syndrome (MAS) and multiple endocrine neoplasia (MEN) type 1 (MEN 1). Like MAS and MEN 1 patients, patients with CNC develop growth hormone (GH)-producing pituitary tumors. Occasionally, these tumors are also prolactin-producing, but there are no isolated prolactinomas or other types of pituitary tumors. In at least some patients with CNC, the pituitary gland is characterized by hyperplastic areas; hyperplasia appears to involve somatomammotrophs only. Hyperplasia most likely precedes the formation of GH-producing adenomas in CNC, as has been suggested in MAS-related somatotropinomas, but has never been seen in MEN 1 patients. In at least one case of a patient with CNC and advanced acromegaly, a GH-producing macroadenoma showed extensive genetic changes at the chromosomal level. So far, half of the patients with CNC have germline inactivating mutations in the PRKAR1A gene; in their pituitary tumors, the normal allele of the PRKAR1A gene is lost. Loss-of-hererozygosity suggests that PRKAR1A, which codes for the regulatory subunit type 1alpha of the cAMP-dependent protein kinase A (PKA) may act as a tumor-suppressor gene in CNC somatomammotrophs. These data provide evidence for a PRKAR1A-induced somatomammotroph hyperpasia in the pituitary tissue of CNC patients; hyperplasia, in turn may lead to additional genetic changes at the somatic level, which then cause the formation of adenomas in some, but not all, patients.

Molecular analysis of the cyclic AMP-dependent protein kinase A (PKA) regulatory subunit 1A (PRKAR1A) gene in patients with Carney complex and primary pigmented nodular adrenocortical disease (PPNAD) reveals novel mutations and clues for pathophysiology: augmented PKA signaling is associated with adrenal tumorigenesis in PPNAD

We studied 11 new kindreds with primary pigmented nodular adrenocortical disease (PPNAD) or Carney complex (CNC) and found that 82% of the kindreds had PRKAR1A gene defects (including seven novel inactivating mutations), most of which led to nonsense mRNA and, thus, were not expressed in patients' cells. However, a previously undescribed base substitution in intron 6 (exon 6 IVS +1G-->T) led to exon 6 skipping and an expressed shorter PRKAR1A protein. The mutant protein was present in patients' leukocytes and tumors, and in vitro studies indicated that the mutant PRKAR1A activated cAMP-dependent protein kinase A (PKA) signaling at the nuclear level. This is the first demonstration of an inactivating PRKAR1A mutation being expressed at the protein level and leading to stimulation of the PKA pathway in CNC patients. Along with the lack of allelic loss at the PRKAR1A locus in most of the tumors from this kindred, these data suggest that alteration of PRKAR1A function (not only its complete loss) is sufficient for augmenting PKA activity leading to tumorigenesis in tissues affected by CNC.

Clinical genetics of multiple endocrine neoplasias, Carney complex and related syndromes

The list of multiple endocrine neoplasias (MENs) that have been molecularly elucidated is growing with the most recent addition of Carney complex. MEN type 1 (MEN 1), which affects primarily the pituitary, pancreas, and parathyroid glands, is caused by mutations in the menin gene. MEN type 2 (MEN 2) syndromes, MEN 2A and MEN 2B that affect mainly the thyroid and parathyroid glands and the adrenal medulla, and familial medullary thyroid carcinoma (FMTC), are caused by mutations in the REToncogene. Finally, Carney complex, which affects the adrenal cortex, the pituitary and thyroid glands, and the gonads, is caused by mutations in the gene that codes for regulatory subunit type 1A of protein kinase A (PKA) (PRKAR1A) in at least half of the known patients. Molecular defects have also been identified in syndromes related to the MENs, like Peutz-Jeghers syndrome (PJS) (the STK11/LKB1 gene), and Cowden (CD; the PTEN gene) and von Hippel-Lindau disease (VHLD; the VHL gene). Although recognition of these syndromes at a young age generally improves prognosis, the need for molecular testing in the diagnostic evaluation of the MENs is less clear. This review presents the newest information on the clinical and molecular genetics of the MENs (MEN 1, MEN 2, and Carney complex), including recommendations for genetic screening, and discusses briefly the related syndromes PJS, CD and VHLD.